HYPOTHESES. 297 



tions of an clastic fluicl in as many respects as is necessary to make the 

 hypothesis a plausible explanation of all or most of the phenomena 

 known at the time, it is nothing strange that they should accord with 

 each other in one respect more. Though twenty such coincidences 

 should occur, tliey would not prove the reality of the undulatory ether ; 

 it would not follow that the phenomena of light were results of the laws 

 of elastic fluids, but at most that they are governed by laws in some 

 measure analogous to these ; which, we may observe, is already cer- 

 tain, from the fact that the hypothesis in question could be for a mo- 

 ment tenable. There are many such harmonics ninning through the 

 laws of phenomena in other respects radically distinct. The remark- 

 able resemblance between the laws of light and many of the laws of 

 heat (while others are as remarkably diflbrent), is a case in point. 

 There is an extraordinary similarity running through the properties, 

 considered generally, of certain substances, as chlorine, iodine, and 

 brome, or sulphur and phosphorus ; so much so that when chemists 

 discover any new property of the one, they not only are not surprised, 

 but expect, to find that the other or others have a'property analogous 

 to it. But the hypothesis that chlorine, iodine, and brome, or that 

 sulphur and phosphorus, are the same substances, would, no doubt, 

 be quite inadmissible. 



I do not, like M. Comte, altogether condemn those who employ them- 

 selves in working out into detail this sort of hypotheses ; it is useful to 

 -ascertain what are the known phenomena to the laws of which those 

 of the subject of inquiry bear the greatest, or even a great analogy, 

 since this may suggest (as in the case of the luminiferous ether it ac~ 

 tually did) experiments to determine whether the analogy which goes 

 so far does not extend still further. But that in doing this, men should 

 imagine themselves to be seriously inquiring whether the hypothesis of 

 an ether, an electric fluid, or the like, is true ; that they should fancy 

 it possible to obtain the assurance that the phenomena are produced 

 in that way and no other ; seems to me, I confess, as unworthy of the 

 present improved conceptions of the methods of physical science, as it 

 does to M. Comte. And at the risk of being charged with want of 

 modesty, I cannot help expressing astonishment that a philosopher of 

 the extraordinary attainments of INIr. Whewell, should have written an 

 elaborate treatise on the philosophy of induction, in which he recog- 

 nizes absolutely no mode of induction except that of trying hypothesis 

 after hypothesis until one is found which fits the phenomena ; which 

 one, when found, is to be assumed as true, with np other reservation 

 than that if on reexamination it should appear to assume more than is 

 needfid for explaining the phenomena, the superfluous part of the, as- 

 sumption sliould be cut off". It is no exaggeration to say that the pro- 

 cess which we have described in these few words, is the beginning, 

 middle, and end of the phitosojdiy of induction as Mr. Whewell con- 

 ceives it. And this without the slightest distinction between the cases 

 in which it may be known beforehand that two different hypotheses 

 cannot lead to the same result, and those in which, for aught we can- 

 ever know, the range of suppositions, all equally consistent with the 

 phenomena, may be infinite. 



§ 7. It is necessary, before quitting the subject of hypotheses, to 

 guard against the appearance of reflecting upon the philosophical eer- 

 P p 



